Reaming tool for broken conduit

ABSTRACT

A reaming tool for reaming a socket in a broken end portion of a cylindrical conduit enlarges the internal diameter of the broken end portion to provide a socket for receiving a male end portion on a repair coupling. The reaming tool is guided by the inner diameter of the conduit while reaming out the broken end portion to a socket diameter that is about midway between the original internal and outer diameters of the conduit.

REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. Ser. No. 10/610,042 filed Jun.30, 2003 now U.S. Pat. No. 7,438,324.

BACKGROUND OF THE INVENTION

This invention relates to a unique reaming tool bit for use in repairingbroken conduit.

Electrical conduit is often embedded in concrete foundations and floorsof commercial and residential buildings, so that electrical wiring canbe run at a later time. Since concrete foundations and floor are pouredbefore any internal walls and other structures are erected, shortsections of conduits extend vertically above the foundation and floor atevery location of an electrical source. In large construction projects,there may be hundreds of exposed conduit ends extending from theconcrete foundation and floors. In the course of construction, theseexposed ends of the electrical conduit are often broken off by workersand equipment in the course of moving materials, erecting interior wallsand other construction activities. The broken conduit ends must berepaired so that additional sections of conduit can be connected to themto complete the installation of the electrical systems.

More often than not, the conduit breaks off near the foundation.Consequently, repairing the broken conduit requires breaking up thefoundation around the broken conduit end to expose the end so that acoupling can be attached over it. Once the coupling is connected to theexposed broken end, the concrete foundation is patched around therepaired conduit.

Repairing the broken conduit embedded in a concrete foundation is anexpensive and time consuming project. A large construction site may havehundreds of exposed conduit ends broken over the course of theconstruction project. Repairing broken conduit ends is a time consumingexpense that is not factored into the cost of most constructionprojects. Consequently, a method for quickly and easily repairing brokenconduit ends is needed.

SUMMARY OF THE INVENTION

The method and specialized repair component for repairing broken conduitends of this invention eliminates the need to break up the concretefoundation around the broken conduit end. The specialized repaircomponents include a reaming bit for milling out and turning down theinside wall of the broken conduit end and repair couplings for joining anew section of conduit to the broken conduit end. The reaming bit isdesigned to be used with any conventional handheld power drill. Thereaming bit mills out the inside of the broken conduit end so that therepair coupling can be inserted into the broken conduit end. With thecoupling fitted into the broken conduit end, a new section of conduitcan be connected completing the repair. Because the coupling is insertedinto the broken end of the conduit instead of over it, the concretefoundation around the conduit does not have to be disturbed.Consequently, this repair method provides a structurally more securerepair.

Accordingly, an advantage of this invention is that the methodeliminates the need to breakup concrete foundations surrounding thebroken conduit end, which greatly reduces the time and expense of therepair.

Another advantage of this invention is that the repair method provides amore structurally secure repair because the concrete foundation remainsundisturbed.

Another advantage of this invention is that the repair method requiresonly two specialized repair components: a reaming bit and a repaircoupling.

Another advantage of this invention is that the reaming bit is designedto be used in any conventional handheld power drill, which is common andreadily available at any construction site.

Another advantage of this invention is that a single user in only a fewminutes can prepare a large number of broken conduit ends for repair,turning down the inside walls of the conduit with the drill mountedreaming bit.

Other advantages will become apparent upon a reading of the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention has been depicted forillustrative purposes only wherein:

FIG. 1 is a perspective view of the reaming bit used in the repairmethod of this invention;

FIG. 2 is an elevated side view of the reaming bit of FIG. 1;

FIG. 3 is an end view of the reaming tool bit of FIG. 1;

FIG. 4 is an exploded view of the reaming tool of FIG. 1;

FIG. 5 is a side view of the reaming tool bit mounted to the chuck of aconventional hand drill being inserted into a broken conduit endembedded in a concrete foundation (shown as a partial side sectionalview);

FIG. 6 is a side view of the reaming tool bit mounted to the chuck of aconventional hand drill being withdrawn from the broken conduit endembedded in a concrete foundation showing the bored out inner wall ofthe broken conduit end (shown as a partial side sectional view);

FIG. 7. is a side sectional view of one embodiment of the repaircoupling of this invention being inserted into the bored out brokenconduit end;

FIG. 8 is a side sectional view of the repair coupling of FIG. 7connecting the repaired conduit end and a new section of conduit;

FIG. 9 is an exploded perspective view of a second embodiment of therepair coupling of this invention;

FIG. 10 is an exploded perspective view of a third embodiment of therepair coupling of this invention;

FIG. 11 is a side sectional view of the repair coupling of FIG. 10connecting the repaired conduit end and a new section of conduit; and

FIG. 12 is a side sectional view of the repair coupling of FIG. 9connecting the repaired conduit end and a new section of conduit.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment herein described is not intended to beexhaustive or to limit the invention to the precise form disclosed. Itis chosen and described to best explain the invention so that othersskilled in the art might utilize its teachings. This invention entails amethod of repairing broken electrical conduit embedded in a concretefoundation without breaking up the foundation and the specializedcomponents used in the repair, namely, a reaming bit and variousembodiments of a repair coupling.

FIGS. 1-4 illustrate the specialized reaming bit of this invention(designated generally as reference numeral 10), which is used to boreout the inner wall of the broken conduit end. Reaming bit 10 has aconventional design and construction common for drill and milling toolsand is intended for use with hand held power drills (reference numeral 8in FIGS. 5 and 6). As shown, reaming bit 10 includes an interchangeablecutting head 20 and pilot head 28 mounted on a mandrel 30. It should benoted that the reaming bit could also be machined from a solid piece ofmetal stock (not illustrated in the figures) within the teaching of thisinvention. The multiple piece design allows interchangeable cuttingheads of various sizes to be used with a standard mandrel assembly.

As shown in FIGS. 1-4, cutting head 20 has a cylindrical body 22 and sixhelical cutting blades 24. Cutting head 20 also has an axial throughbore 21, through which the mandrel extends. Each cutting blade has acutting edge and a cutting face that allows the material shaved from theconduit wall to be expelled upward. The outer diameter of cutting head20 is sized to mill out and remove material from the inner wall of thebroken conduit end to reduce the wall thickness to accommodate therepair coupling. Generally, cutting head 20 is sized to removeapproximately one half the thickness of the conduit wall. Pilot head 28has an axial through bore 29, through which mandrel 30 extends. Mandrel30 has an integral cylindrical shoulder stop 32 and axial shank 34 thatextends axially from opposite ends of the shoulder stop. As shown,cutting head 20 and pilot head 28 are mounted to the proximal end ofshank 34 by a bolt 36 that is turned into a threaded axial bore 35 inshank 34. The distal end of shank 34 is used to secure the reaming bitto the chuck of a power drill. A pin 38 extends through lateral bores incutting head 20 and shank 34 to secure and prevent the cutting head fromturning on the mandrel. The outer diameter of the pilot head 28 andshoulder stop 32 are sized to accommodate the inner and outer diametersof the broken conduit end, such that the pilot head is insertable intothe broken conduit end and the oversized shoulder stop will abut againstthe conduit end.

FIGS. 7-14 illustrate different embodiments of the repair couplings ofthis invention, which are used to join the broken conduit end to a newsection of conduit. The repair couplings join the broken conduit ends tonew sections of conduit. Because electrical conduit is available invarious standardized diameter sizes and wall thicknesses, the repaircouplings of this invention are intended to be dimensioned intostandardized sizes that accommodate the various diameter sizes andconventions of both plastic and metal electrical conduit. For example,different sizes of repair couplings will be used with each standardizeddiameter of the electrical conduit, i.e. 1 inch, ¾ inch, etc . . . . Inaddition, the teachings of this invention encompass variations in therepair coupling that will connect conduit of both identical (straightcouplings) and differing diameter sizes (reducer couplings).

FIGS. 7 and 8 illustrate the repair coupling of this inventiondesignated by reference numeral 40. Repair coupling 40 has a singlepiece construction and is ideally formed from a plastic material, suchas acrylonitrile-butadiene-styrene (ABS) or polyvinylchloride (PVC), butcan also be cast from a metal such as brass, aluminum or steel. Repaircoupling 40 has a tubular body with a larger diameter female end 42 anda smaller diameter male end 44. Repair coupling 40 is dimensioned sothat male end 44 can be inserted directly into the reamed conduit endwith a snug fit and a new section of conduit can be inserted into thefemale end. As shown, the thickness the of sidewall of male end 44 aresignificantly thinner than the sidewall of female end 42, and isapproximately one half the thickness of the sidewall of the reamedconduit end in which it is inserted. For a ¾ inch sized repair coupling,the sidewall thickness at male end 44 is approximately 0.0640 inches(generally ranging between 0.0600-0.0700 inches) and the sidewallthickness at the female end is approximately 0.1260 inches (generallyranging between 0.1200-0.1300 inches). For a one inch sized repaircoupling, the sidewall thickness at male end 44 is approximately 0.0675inches (generally ranging from 0.0670-0.0680 inches) and the sidewallthickness at the female end is approximately 0.1425 (generally rangingfrom 0.1400-0.1500 inches). The tubular sidewalls of repair coupling 40form a cylindrical passage therethrough. As shown in FIG. 8, the innerdiameter of female end 42 is slightly greater than the inner diameter ofmale end 44, which forms a shoulder 46. Shoulder 46 acts as a stop ofthe new conduit section.

FIGS. 9-12 illustrate another embodiment of the repair coupling of thisinvention (designated as reference numeral 50). Repair coupling 50 has atwo piece component design that includes an inner sleeve 52 and an outercollar (designated as 60 in FIGS. 9 and 12 and 70 in FIGS. 10 and 11).Both the inner sleeve 52 and outer collar 60 and 70 may be formed from aplastic material, such as acrylonitrile-butadiene-styrene (ABS) orpolyvinylichlioride (PVC), or cast from a metal such as brass, aluminumor steel. Again, repair coupling 50 is intended to be sized anddimensioned into standardize sizes that accommodate the various diametersizes and conventions of both plastic and metal electrical conduit.Generally, inner sleeve 52 is constructed of plastic and outer collars60 and 70 are constructed of metal and is a conventional conduitconnector of standard size. Inner sleeve 52 has a generally tubular bodywith a smooth axial bore 53. As shown in FIGS. 11 and 12, one end 54 ofsleeve 52 is dimensioned for insertion into the reamed conduit end whilethe other end 56 is dimensioned for insertion into one end of outercollar 60 or 70. As shown, outer collars 60 and 70 differ only in thatcollar 60 has a threaded mouth 62 for receiving threaded electricalconduit 6 a(Fig. 12), while collar 70 has a smooth mouth 72 forreceiving non-threaded conduit 6 (FIG. 11), such as EMT (electricalmetallic tubing). A small screw 74 is turned into a threaded side bore73 in collar 70 to secure the new section of conduit into the collar.

FIGS. 5-12 illustrate the various steps in the method of this inventionfor repairing the broken conduit end designated generally as referencenumeral 2 embedded in a concrete foundation 3. Often the broken conduitend extending from the concrete foundation is jagged and uneven and mayextend some distance above the foundation. Initially, broken conduit end3 is often cut at the surface of foundation 3 to provide a clean andstraight end for repair, as shown in FIG. 5. As illustrated in FIGS. 5and 6, reaming bit 10 is used to mill out the inside of the brokenconduit end 2. Pilot head 28 guides and centers cutting head 20 as auser inserts reaming bit 10 into broken conduit end 2. The user insertsreaming bit 10 into the broken conduit end until shoulder stop 32 abutsthe end of the conduit, whereby the rotating cutting head 20 reams outthe inside of sidewall 4 to reduce the thickness of the conduit sidewallto a set depth substantially equal to the length of the cutting head.When reaming bit 10 is withdrawn from broken conduit end 2, the insideof conduit sidewall 4 has been reamed out (turned down) to receive therepair coupling. Next, the repair coupling is fitted to the reamedconduit end 2 (FIGS. 6 and 7). Typically, the male end of the repaircoupling is hand pressed into the reamed conduit end and a jointcompound is used to permanently join the repair coupling to the conduit.The last step, illustrated in FIGS. 8, 11 and 12 is to connect a newsection of conduit designated as reference numeral 6 in FIGS. 8 and 11,and as 6 a in FIG. 12 to the repair coupling. Again a joint compound istypically used to join the new conduit section 6 while conduit section 6a is joined by way of cooperating threads. Once the new conduit sectionis joined, wiring can be run within the repaired conduit system.

ADVANTAGES

One skilled in the art will note several advantages of this repairmethod and specialized repair components of this invention. The methodeliminates the need to breakup concrete foundations surrounding thebroken conduit end, which greatly reduces the time and expense of therepair. The repair method requires only the specialized reaming bit anda repair coupling. The reaming bit is deigned to be used in anyconventional handheld power drill, which is common and readily availableat any construction site. In a matter of minutes, a single user canprepare a large number of broken conduit ends for repair, turning downthe inside walls of the conduit with the drill mounted reaming bit. Thereaming bit is a relatively small component that can be carried byworkers with little inconvenience. The repair method also does notrequire the repairer to carry any other additional tools.

The repair couplings are small, inexpensive piece parts, whose cost issignificantly less than the cost of repairing a concrete foundation. Therepair couplings are generally constructed from plastics and can beproduced in various sizes in large quantities with great costeffectiveness. The single piece design of the first embodiment of therepair coupling is well suited for low cost plastic construction. Thetwo piece design of the repair coupling of the second embodiment allowsthe combination of both plastic and metal conduit. Building codes oftenrequire metal conduit be run from the foundation up. Consequently,plastic conduit must often be mated with metal conduit at thefoundation. The two piece design of the second embodiment allows plasticinner sleeves to be mated with plastic or metal collars. The repaircoupling provides a convenient interconnection between the plasticconduit inside the foundation and metal conduit run above the foundationif required. In addition, the inner sleeves are designed to fit intoconventional collars that are common and readily available in theindustry further reducing costs.

It should be noted that the repair method of this invention alsoprovides a more structurally secure repair. Patched concrete foundationnever has the integrity of the original foundation and is subject tocracks, as well as an unsightly appearance. Consequently, eliminatingthe need to break up and patch the concrete foundations is a significantadvantage of this repair method. While the inside of the sidewalls ofthe conduit are turned down, the concrete foundation, which is leftundisturbed around the conduit end, provides sufficient structuralsupport to the repair coupling and new conduit sections. Because theconcrete foundation surrounds the broken conduit end, the turned downsidewall of the conduit is reinforced from outside forces that mayfracture or crack the conduit.

It is understood that the above description does not limit the inventionto the details given, but may be modified within the scope of thefollowing claims.

1. An apparatus for joining a new conduit to an embedded conduit havinginner and outer diameters, the apparatus comprising: a mandrel includinga cylindrical shoulder stop with a proximal end surface and a distal endsurface, the mandrel further including a shank that is integral with theshoulder stop, the shank having a proximal end portion that projectsaxially from the proximal end surface of the shoulder stop and a distalend portion that is securable in a chuck and projects axially from thedistal end surface of the shoulder stop; a cylindrical cutting headhaving an outer diameter between the inner and outer diameters of theembedded conduit, and further having a proximal end surface, a distalend surface, and an axial through bore for mounting the cutting head onthe mandrel in an installed position in which the proximal end portionof the shank extends through the bore and the distal end surface of thecutting head abuts the proximal end surface of the shoulder stop; and apilot head having an outer diameter matching the inner diameter of theconduit, and further having a distal end surface and an axial throughbore for mounting the pilot head on the mandrel in an installed positionin which the distal end surface of the pilot head abuts the proximal endsurface of the cutting head.
 2. An apparatus as defined in claim 1further comprising a tubular coupling having a male section with anouter diameter matching the outer diameter of the cutting head so as totake an installed position fitted closely within a socket formed in theembedded conduit by the cutting head, and having a female section withan inner diameter sized for the new conduit to take an installedposition fitted closely within the female section of the coupling.
 3. Anapparatus for joining a new conduit to an embedded conduit having innerand outer diameters, the apparatus comprising: a mandrel including acylindrical shoulder stop with a proximal end surface and a distal endsurface, the mandrel further including a shank having a proximal endportion that projects axially from the proximal end surface of theshoulder stop and a distal end portion that is securable in a chuck andprojects axially from the distal end surface of the shoulder stop; acylindrical cutting head having an outer diameter between the inner andouter diameters of the embedded conduit, and further having a proximalend surface, a distal end surface, and an axial through bore formounting the cutting head on the mandrel in an installed position inwhich the proximal end portion of the shank extends through the bore andthe distal end surface of the cutting head abuts the proximal endsurface of the shoulder stop; and a pilot head having an outer diametermatching the inner diameter of the conduit, and further having a distalend surface and an axial through bore for mounting the pilot head on themandrel in an installed position in which the distal end surface of thepilot head abuts the proximal end surface of the cutting head; whereinthe cutting head and the pilot head are located in their installedpositions on the mandrel and are held in place by a screw threadedattachment.